In conjunction the development of cardiac pacemakers for generating tissue stimulation pulses, endocardial electrodes were developed for transferring stimulation pulses from the pacemaker to the heart. In a typical application, the electrode is inserted into and forced through a vein until the electrode tip enters the heart atrium. Electrodes designed to provide stimulation pulses to the heart wall defining the ventrical chamber are inserted through the heart valve separating the atrium from the ventrical until the electrode tip engages the heart trabeculae within the ventrical. With the advent of pacing within the atrium, a J-shaped electrode was developed so that the electrode tip will be positioned against an upper portion of the atrium, an electrode portion adjacent to the tip being formed in the shape of a "J". It is desirable that this "J" portion have a sufficiently stiff body for ease of insertion and maintenance of the electrode tip in the desired location. However, the stiffness required to maintain the "J" configuration is undesirable in high stress points, such as the upper chest region where the electrode is ligated, stretched, or otherwise highly stressed. Thus electrodes have been developed having greater stiffness in lower stress regions and greater resistance to flexural failure in high stress areas. In order to achieve the greater stiffness, one prior art electrode utilizes coils surrounding the portion of the electrode that needs stiffening. A disadvantage of this approach is that it results in a larger electrode cross-sectional area in the portion where stiffening is required, thereby making veinous insertion of the electrode more difficult. Another prior art electrode utilizes a thicker electrode encasement material over the portion of the electrode to be stiffened. This type electrode also has a larger cross-sectional area for the stiffened portion than for the non-stiffened portion.